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  <div class="section" id="module-curses.ascii">
<h1>16.11. <tt class="xref docutils literal"><span class="pre">curses.ascii</span></tt> &#8212; Utilities for ASCII characters<a class="headerlink" href="#module-curses.ascii" title="Permalink to this headline">¶</a></h1>
<p>
<span class="versionmodified">New in version 1.6.</span></p>
<p>The <tt class="xref docutils literal"><span class="pre">curses.ascii</span></tt> module supplies name constants for ASCII characters and
functions to test membership in various ASCII character classes.  The constants
supplied are names for control characters as follows:</p>
<table border="1" class="docutils">
<colgroup>
<col width="23%" />
<col width="77%" />
</colgroup>
<thead valign="bottom">
<tr><th class="head">Name</th>
<th class="head">Meaning</th>
</tr>
</thead>
<tbody valign="top">
<tr><td><tt class="xref docutils literal"><span class="pre">NUL</span></tt></td>
<td>&nbsp;</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">SOH</span></tt></td>
<td>Start of heading, console interrupt</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">STX</span></tt></td>
<td>Start of text</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">ETX</span></tt></td>
<td>End of text</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">EOT</span></tt></td>
<td>End of transmission</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">ENQ</span></tt></td>
<td>Enquiry, goes with <tt class="xref docutils literal"><span class="pre">ACK</span></tt> flow control</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">ACK</span></tt></td>
<td>Acknowledgement</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">BEL</span></tt></td>
<td>Bell</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">BS</span></tt></td>
<td>Backspace</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">TAB</span></tt></td>
<td>Tab</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">HT</span></tt></td>
<td>Alias for <tt class="xref docutils literal"><span class="pre">TAB</span></tt>: &#8220;Horizontal tab&#8221;</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">LF</span></tt></td>
<td>Line feed</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">NL</span></tt></td>
<td>Alias for <tt class="xref docutils literal"><span class="pre">LF</span></tt>: &#8220;New line&#8221;</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">VT</span></tt></td>
<td>Vertical tab</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">FF</span></tt></td>
<td>Form feed</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">CR</span></tt></td>
<td>Carriage return</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">SO</span></tt></td>
<td>Shift-out, begin alternate character set</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">SI</span></tt></td>
<td>Shift-in, resume default character set</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">DLE</span></tt></td>
<td>Data-link escape</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">DC1</span></tt></td>
<td>XON, for flow control</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">DC2</span></tt></td>
<td>Device control 2, block-mode flow control</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">DC3</span></tt></td>
<td>XOFF, for flow control</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">DC4</span></tt></td>
<td>Device control 4</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">NAK</span></tt></td>
<td>Negative acknowledgement</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">SYN</span></tt></td>
<td>Synchronous idle</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">ETB</span></tt></td>
<td>End transmission block</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">CAN</span></tt></td>
<td>Cancel</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">EM</span></tt></td>
<td>End of medium</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">SUB</span></tt></td>
<td>Substitute</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">ESC</span></tt></td>
<td>Escape</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">FS</span></tt></td>
<td>File separator</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">GS</span></tt></td>
<td>Group separator</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">RS</span></tt></td>
<td>Record separator, block-mode terminator</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">US</span></tt></td>
<td>Unit separator</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">SP</span></tt></td>
<td>Space</td>
</tr>
<tr><td><tt class="xref docutils literal"><span class="pre">DEL</span></tt></td>
<td>Delete</td>
</tr>
</tbody>
</table>
<p>Note that many of these have little practical significance in modern usage.  The
mnemonics derive from teleprinter conventions that predate digital computers.</p>
<p>The module supplies the following functions, patterned on those in the standard
C library:</p>
<dl class="function">
<dt id="curses.ascii.isalnum">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">isalnum</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.isalnum" title="Permalink to this definition">¶</a></dt>
<dd>Checks for an ASCII alphanumeric character; it is equivalent to <tt class="docutils literal"><span class="pre">isalpha(c)</span> <span class="pre">or</span>
<span class="pre">isdigit(c)</span></tt>.</dd></dl>

<dl class="function">
<dt id="curses.ascii.isalpha">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">isalpha</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.isalpha" title="Permalink to this definition">¶</a></dt>
<dd>Checks for an ASCII alphabetic character; it is equivalent to <tt class="docutils literal"><span class="pre">isupper(c)</span> <span class="pre">or</span>
<span class="pre">islower(c)</span></tt>.</dd></dl>

<dl class="function">
<dt id="curses.ascii.isascii">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">isascii</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.isascii" title="Permalink to this definition">¶</a></dt>
<dd>Checks for a character value that fits in the 7-bit ASCII set.</dd></dl>

<dl class="function">
<dt id="curses.ascii.isblank">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">isblank</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.isblank" title="Permalink to this definition">¶</a></dt>
<dd>Checks for an ASCII whitespace character.</dd></dl>

<dl class="function">
<dt id="curses.ascii.iscntrl">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">iscntrl</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.iscntrl" title="Permalink to this definition">¶</a></dt>
<dd>Checks for an ASCII control character (in the range 0x00 to 0x1f).</dd></dl>

<dl class="function">
<dt id="curses.ascii.isdigit">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">isdigit</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.isdigit" title="Permalink to this definition">¶</a></dt>
<dd>Checks for an ASCII decimal digit, <tt class="docutils literal"><span class="pre">'0'</span></tt> through <tt class="docutils literal"><span class="pre">'9'</span></tt>.  This is equivalent
to <tt class="docutils literal"><span class="pre">c</span> <span class="pre">in</span> <span class="pre">string.digits</span></tt>.</dd></dl>

<dl class="function">
<dt id="curses.ascii.isgraph">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">isgraph</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.isgraph" title="Permalink to this definition">¶</a></dt>
<dd>Checks for ASCII any printable character except space.</dd></dl>

<dl class="function">
<dt id="curses.ascii.islower">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">islower</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.islower" title="Permalink to this definition">¶</a></dt>
<dd>Checks for an ASCII lower-case character.</dd></dl>

<dl class="function">
<dt id="curses.ascii.isprint">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">isprint</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.isprint" title="Permalink to this definition">¶</a></dt>
<dd>Checks for any ASCII printable character including space.</dd></dl>

<dl class="function">
<dt id="curses.ascii.ispunct">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">ispunct</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.ispunct" title="Permalink to this definition">¶</a></dt>
<dd>Checks for any printable ASCII character which is not a space or an alphanumeric
character.</dd></dl>

<dl class="function">
<dt id="curses.ascii.isspace">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">isspace</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.isspace" title="Permalink to this definition">¶</a></dt>
<dd>Checks for ASCII white-space characters; space, line feed, carriage return, form
feed, horizontal tab, vertical tab.</dd></dl>

<dl class="function">
<dt id="curses.ascii.isupper">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">isupper</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.isupper" title="Permalink to this definition">¶</a></dt>
<dd>Checks for an ASCII uppercase letter.</dd></dl>

<dl class="function">
<dt id="curses.ascii.isxdigit">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">isxdigit</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.isxdigit" title="Permalink to this definition">¶</a></dt>
<dd>Checks for an ASCII hexadecimal digit.  This is equivalent to <tt class="docutils literal"><span class="pre">c</span> <span class="pre">in</span>
<span class="pre">string.hexdigits</span></tt>.</dd></dl>

<dl class="function">
<dt id="curses.ascii.isctrl">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">isctrl</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.isctrl" title="Permalink to this definition">¶</a></dt>
<dd>Checks for an ASCII control character (ordinal values 0 to 31).</dd></dl>

<dl class="function">
<dt id="curses.ascii.ismeta">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">ismeta</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.ismeta" title="Permalink to this definition">¶</a></dt>
<dd>Checks for a non-ASCII character (ordinal values 0x80 and above).</dd></dl>

<p>These functions accept either integers or strings; when the argument is a
string, it is first converted using the built-in function <a title="ord" class="reference external" href="functions.html#ord"><tt class="xref docutils literal"><span class="pre">ord()</span></tt></a>.</p>
<p>Note that all these functions check ordinal bit values derived from the  first
character of the string you pass in; they do not actually know anything about
the host machine&#8217;s character encoding.  For functions  that know about the
character encoding (and handle internationalization properly) see the
<a title="Common string operations." class="reference external" href="string.html#module-string"><tt class="xref docutils literal"><span class="pre">string</span></tt></a> module.</p>
<p>The following two functions take either a single-character string or integer
byte value; they return a value of the same type.</p>
<dl class="function">
<dt id="curses.ascii.ascii">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">ascii</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.ascii" title="Permalink to this definition">¶</a></dt>
<dd>Return the ASCII value corresponding to the low 7 bits of <em>c</em>.</dd></dl>

<dl class="function">
<dt id="curses.ascii.ctrl">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">ctrl</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.ctrl" title="Permalink to this definition">¶</a></dt>
<dd>Return the control character corresponding to the given character (the character
bit value is bitwise-anded with 0x1f).</dd></dl>

<dl class="function">
<dt id="curses.ascii.alt">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">alt</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.alt" title="Permalink to this definition">¶</a></dt>
<dd>Return the 8-bit character corresponding to the given ASCII character (the
character bit value is bitwise-ored with 0x80).</dd></dl>

<p>The following function takes either a single-character string or integer value;
it returns a string.</p>
<dl class="function">
<dt id="curses.ascii.unctrl">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">unctrl</tt><big>(</big><em>c</em><big>)</big><a class="headerlink" href="#curses.ascii.unctrl" title="Permalink to this definition">¶</a></dt>
<dd>Return a string representation of the ASCII character <em>c</em>.  If <em>c</em> is printable,
this string is the character itself.  If the character is a control character
(0x00-0x1f) the string consists of a caret (<tt class="docutils literal"><span class="pre">'^'</span></tt>) followed by the
corresponding uppercase letter. If the character is an ASCII delete (0x7f) the
string is <tt class="docutils literal"><span class="pre">'^?'</span></tt>.  If the character has its meta bit (0x80) set, the meta bit
is stripped, the preceding rules applied, and <tt class="docutils literal"><span class="pre">'!'</span></tt> prepended to the result.</dd></dl>

<dl class="data">
<dt id="curses.ascii.controlnames">
<tt class="descclassname">curses.ascii.</tt><tt class="descname">controlnames</tt><a class="headerlink" href="#curses.ascii.controlnames" title="Permalink to this definition">¶</a></dt>
<dd>A 33-element string array that contains the ASCII mnemonics for the thirty-two
ASCII control characters from 0 (NUL) to 0x1f (US), in order, plus the mnemonic
<tt class="docutils literal"><span class="pre">SP</span></tt> for the space character.</dd></dl>

</div>


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